This invention relates to a heat exchanger which contains catalyzed screens and/or felt metal cloth for removing materials such as pollutants and other impurities from exhaust gases another fluids while simultaneously recovering heat energy from the gaseous exhaust or other fluids.
In the past, heat exchangers have been used to recover energy from exhaust gases so that this energy can be reused for other purposes. Plate type heat exchangers are commonly used for achieving an indirect heat transfer between two fluids circulating at different temperatures. These heat exchangers generally consist of a plurality of spaced parallel plates welded or otherwise attached between two end plates to define parallel passages. Manifolds are attached to the ends of the passages to direct each fluid to alternate passages so that each plate forms a heat conducting interface between the two fluids.
Recuperative heat exchangers have been used to remove impurities from exhaust gases. These exhaust gases contain various pollutants, such as NOx, CO and VOC type gases. In the past, various heat exchangers have attempted to remove the pollutant gases from the exhaust gas by having a catalyst coated on the heat exchanger plates. For example, in the Winegar, U.S. Pat. No. 5,738,024, a catalyst is coated on heat exchanger elements. Also, in the Fromson et al., U.S. Pat. No. 5,711,071, an extended heated exchange surface or fin of a heat exchanger has a catalyst material firmly anchored as nodules formed on the fins. In the Fromson et al. patent, the metal surface containing a catalyst material is not formed as an integral part of the heat exchanger. Rather, in the Fromson et al. ""071 patent, the catalyst material is on a grid structure or screen or wire mesh structure which is located adjacent and downstream from the heat exchanger with respect to the direction of air flow, so that the air flowing over and through the catalyst structure is air that first comes through and is heated by the heat exchanger. However, there is difficulty when utilizing such heat exchanges since much of the pollutant material in the exhaust gases is not removed from the exhaust gas. Accordingly, the exhaust gases are not sufficiently cleaned to meet either emission standards or to be reused in a recuperative heat exchanger. Accordingly, it is the object of the present invention to provide a heat exchanger with a catalyst which substantially removes pollutants from exhaust gases.
It is a further object of the invention to provide a heat exchanger where a mesh or screen catalytic material is placed within the passageways of a heat exchanger material, such that exhaust gases come into contact with and flow through the catalyst coated mesh material as the heat is being removed from the exhaust gases.
It is a further object of the invention to provide a heat exchanger having high efficiency or removing materials such as pollutants and other impurities and for recovering energy from exhaust gases so the energy can be used for other processes.
Other objects and advantages of the invention will be apparent from the following detailed description of the invention.
This invention is directed to a heat exchanger with a catalyst having a heat exchanger core composed of a plurality of spaced apart plate members. The core is disposed for receiving high temperature exhaust gases. The plate members define a set of first passageways for receiving exhaust gases and a plurality of second passageways through which cooling heat transfer gases flow. A catalyst material is positioned in the first passageways such that the exhaust gases pass through the catalyst material as the heat energy is being recovered from the exhaust gases. The catalyst material comprises a support material such as a mesh screen or felt metal cloth coated or impregnated with a suitable catalytic agent.